The yeast Candida albicans is a normal resident of the human digestive tract. It is also the most common fungal pathogen of humans, causing both mucosal and systemic infections, particularly in immune compromised patients. This proposal seeks to understand how C. albicans orchestrates the formation of biofilms - resilient, surface-associated, and organized groups of cells. Biofilm formation is medically relevant because new C. albicans infections are highly correlated with implanted medical devices, which provide efficient substrates for biofilm formation. Our approach to the study of biofilm formation is through dissection of the transcriptional circuitry that controls this process. Our long-term goal s to understand how the individual target genes of the circuit contribute to the key properties of biofilms, how mixed biofilm are formed between C. albicans and certain bacterial species, and how the biofilm transcription network differs among pathogenic species closely related to C. albicans.